Bacterial Lipopolysaccharides Exacerbate Neurogenic Heterotopic Ossification Development

Area of Science:

• Neuroscience
• Immunology
• Orthopedics

Background:

• Neurogenic heterotopic ossifications (NHO) are bone formations in muscles post-central nervous system (CNS) injury.
• NHO prevalence is higher with infections, but the causal link is unclear.

Purpose of the Study:

• To investigate the role of gram-negative bacterial infections in NHO development.
• To elucidate the molecular mechanisms linking infection to NHO.

Main Methods:

• A mouse model of spinal cord injury (SCI) was used to induce NHO.
• Lipopolysaccharides (LPS) were administered to assess their effect on NHO.
• Toll-like receptor-4 (TLR4) signaling pathways (TRIF/MYD88) were analyzed.
• Human fibro-adipogenic progenitors were cultured with LPS.
• A retrospective study in traumatic brain injury patients was conducted.

Main Results:

• LPS exacerbated NHO development in a TLR4-dependent manner, via the TRIF pathway.
• SCI did not cause gut barrier dysfunction or endotoxemia in the mouse model.
• LPS increased osteoblast marker expression in human cells.
• Gram-negative Pseudomonas infections were associated with NHO in patients.

Conclusions:

• Gram-negative bacterial infections functionally contribute to NHO development.
• TLR4 and TRIF signaling are key mediators.
• Infection management is critical for NHO prevention in CNS-injured patients.